Solar panels are used widely to generate electricity or to generate heat directly. Conventional solar panels are positioned facing the sun, as illustrated in FIG. 1. Referring to FIG. 1, a solar panel array 100 may include a plurality of solar panels 101a, 101b, . . . . The individual solar panels are usually positioned substantially in a same plane that substantially faces the sun 103. To maximize the efficiency of collecting solar energy, it is usually preferred that the solar panels are as vertical to the sun light direction 102 as possible. In some prior art, the solar panels are driven, using motors, to follow the sun. A significant portion of sun light is reflected back to the space, as shown by arrow 104. Anti-reflecting (AR) coatings have been used to lower the reflection.